Microsoft platforms chief Johnson is leaving

Breaking news: In a surprise move, Kevin Johnson, the president of Microsoft’s Platforms & Services Division, is leaving the company, Microsoft said this afternoon. Johnson, who reported to Microsoft Chief Executive Steve Ballmer, headed groups including the Windows team and the company’s consumer online services, where Microsoft has struggled to keep up with Google in the critical Internet search market.

In another shakeup, Microsoft said it will be splitting the Platforms & Services Division into two parts, Windows/Windows Live and Online Services, both of which will report directly to Ballmer. The Wall Street Journal reports that Johnson is leaving to run Juniper Networks.

Update, 4:58 p.m. Analysts are still sorting out the implications of Johnson’s surprise departure. The fact that Microsoft didn’t already have a replacement lined up suggests that it may have been a relatively sudden announcement on Johnson’s part, said Matt Rosoff, an analyst with Kirkland-based research firm Directions on Microsoft.

“Usually, when Microsoft makes an executive change of this magnitude, they have someone lined up as a replacement, and in this case they didn’t,” Rosoff said.

Another possibility is that Johnson’s departure is clearing the way for a partnership or deal with another company, Rosoff said. Microsoft has continued to leave the door open to a deal for Yahoo’s search business, and recent reports had the Redmond company talking with Time Warner Inc. about a possible combination or alliance with its AOL unit.

One thing is clear: Ballmer will have more direct oversight of some of the company’s most important businesses. Microsoft says senior vice presidents Steven Sinofsky, Jon DeVaan and Bill Veghte will report directly to the Microsoft CEO from the Windows and Windows Live side of the division. For the Online Services Business, which includes the company’s search and advertising initiatives, the company says it will conduct an internal and external search for a new senior leader.

The news release says Johnson “will work to ensure a smooth transition” but doesn’t give a timeline. One person familiar with the situation noted that Johnson has long had CEO aspirations. With Ballmer planning to stay at Microsoft for years to come, that meant he needed to look elsewhere.